Verified answer

4-4.-15.13=

784

4+-28/30=

32/30 e -24/30

x²+2x-3=

4-4.1.-3=16

4+-4/2

4 e -1

2x²-x+6=4x-4

2x²-5x+2=

25-4.4=9

1+-3/2=

2 e -1

15x²+2x-13=0

∆=2²-4(15)(-13)=

4+780=784

√784=18

x=(-2±18)/30

x'=-20/30=-2/3

x"=16/30=8/15